This invention relates to paperboard containers, particularly to corrugated paperboard containers. More particularly, this invention relates to a variable volume container having increased stack strength.
Corrugated paperboard containers--primarily corrugated boxes--are used by producers of many types of products to store their products and to ship them to customers. During such storage and shipment, the number of boxes that can be stacked in a single vertical column is limited by the stack strength of one box, which is defined as the amount of weight that can be stacked on top of the box before it will deform. For some products it does not matter if the box deforms and transfers at least part of the weight of the boxes above it to its contents. However, for other more fragile types of products it is undesirable for any of the weight of the boxes above to be transferred to the contents. In either case, it is desirable to be able to increase the stack strength of the box as much as possible.
It is known to provide different types of inserts, such as corner posts, in corrugated boxes to increase their stack strength. The inserts have been made of folded corrugated paperboard, of wood, and of polymeric materials such as polystyrene foam. However, use of such inserts adds additional steps to the erection of a box if the inserts are to be added before the box is loaded, or to loading of the box if the inserts are wrapped around the load before the load is inserted into the box. In addition, it is necessary to keep an inventory of inserts in addition to an inventory of boxes.
Most industries produce goods of different sizes or, if they produce small goods, ship their goods in lots of different sizes. However, because of the nature of machinery and tooling, the different size goods frequently have dimensions in common, or the different stacked lots of small goods might have dimensions in common. For example, a manufacturer of household refrigerators may produce several different models of refrigerators of different sizes, but most or all will probably have the same height, and several groups of models may also have the same depth. Nevertheless, the refrigerator manufacturer must have an inventory of boxes of as many different sizes as there are models of refrigerators. Similarly, a manufacturer of light bulbs, all of which are approximately the same size, may ship them in different sized stacked lots, many or all of which have the same horizontal area or the same height, differing only in the other dimensions. Yet the light bulb manufacturer must have an inventory of boxes for each different lot size. Further, in both cases the box must be loaded from one open end and, in the case of a heavy object such as a refrigerator, the box must be lifted, open end down, completely over the top of the object and brought down over the object.
It would be desirable to be able to provide a container which has increased stack strength to reduce or eliminate the need for inserts and the extra step needed to assemble and pack inserts into containers.
It would also be desirable to be able to produce a variable volume container to reduce the inventory of containers that must be kept on hand to pack a variety of articles of different sizes.
It would further be desirable to provide a carton that can be easily erected about large articles.